Wireless Mesh Network Latency Reduction via Hop Layer Parity

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Solution Overview

Problem

Conventional wireless mesh networks experience high latency due to battery-powered nodes (BPDs) needing to wait for extended periods to re-transmit data packets, especially when communication windows are far apart, leading to delayed data propagation across the network, which can result in 'stale' data by the time it reaches continuously-powered nodes (CPDs).

Innovation Solution

Configuring nodes to receive and transmit data packets within specific sub-intervals of a communication window based on hop layer parity, allowing data to traverse multiple hops within a single communication window by interleaving transmit and receive patterns, thereby reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If battery-powered nodes (BPDs) remain powered off for long intervals to conserve power, then energy consumption is reduced, but data transmission latency increases

Engineering Contradiction:

Improvepower consumptionVSAvoiddata transmission latency

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The communication window is segmented into multiple non-overlapping sub-intervals (first sub-interval, second sub-interval, third sub-interval) within each communication window. Nodes are configured to receive and transmit data during specific sub-intervals based on their hop layer, allowing multiple hops to occur within a single communication window while BPDs remain powered off for the majority of the time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Nodes are pre-configured with knowledge of which sub-intervals they should receive and transmit data during, based on their assigned hop layer. This preliminary configuration allows nodes to immediately engage in data transmission when their designated sub-interval arrives, eliminating the need to wait for subsequent communication windows and reducing latency.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If BPDs wait for subsequent communication windows to re-transmit data packets, then power consumption is reduced, but data propagation speed decreases

Engineering Contradiction:

Improvebattery power consumptionVSAvoiddata propagation speed

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

Data transmission occurs periodically at specific sub-intervals within communication windows, with each node assigned to specific periodic time slots based on its hop layer. This structured periodic action allows efficient use of battery power while maintaining predictable data propagation timing.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent introduces a temporal dimension by dividing the communication window into multiple sub-intervals and assigning nodes to different time slots based on their hop layer. This dimensional organization allows multiple hops to occur sequentially within a single communication window, increasing data propagation speed without requiring continuous node operation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Loss of energy

If communication windows are separated by long periods, then battery-powered nodes can conserve energy, but network latency increases

Engineering Contradiction:

Improveenergy loss during idle periodsVSAvoidwait time between communication windows

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

Multiple data transmissions across multiple hops are merged into a single communication window by utilizing different sub-intervals within that window. Nodes at different hop layers transmit data during different sub-intervals, allowing data to traverse multiple hops without requiring multiple separate communication windows, thus reducing the idle time between windows while conserving energy.

Inventive Principle:

Principle #5Merging (Combining)

4Speed

If nodes transmit data immediately after receiving it, then data propagation speed increases, but coordination complexity increases

Engineering Contradiction:

Improvedata re-transmission speedVSAvoidcommunication coordination complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

Each node is assigned specific receive and transmit sub-intervals based on its local hop layer assignment. Nodes at even hop layers have different sub-interval assignments than nodes at odd hop layers, creating a localized quality difference that prevents collisions and simplifies coordination while enabling immediate re-transmission when the designated sub-interval arrives.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10397821B2Reduced latency operating modes for wireless mesh networks

Publication Date: 2019.08.27 ITRON NETWORKED SOLUTIONS INC

AI summary

A wireless mesh network includes a mesh of continuously-powered devices (CPDs) and a mesh of battery-powered devices (BPDs). The BPDs are organized into hop layers based on hopping distance to the mesh of CPDs. In a medium latency communication mode, a given BPD receives data during a receive window that is scheduled to occur within either the first half of a communication window or the second half of the communication window, depending on the parity of the hop layer where the BPD resides. With this approach, a data packet can traverse one hop of the BPD mesh per communication window. In a low-latency communication mode, a given BPD receives and transmits data according to an alternating pattern that depends on the parity of the hop layer where the node resides. With this technique, a data packet can traverse multiple hops of the BPD mesh within a single communication window. These techniques also are applicable to CPDs and other types of nodes as well.